Internally curing cement based materials

Abstract

A method of curing cementitious material comprising added a carboxylated bleached wood pulp fiber to the material during mixing. The fiber has a carboxyl content of from 10 to 70 meq/100 g cellulose fiber. The fibers are 0.1 to 5% by weight of the dry weight of the cementitious material. The structure produced by the method. The autogenous shrinkage of the cementitious material is reduced.

The invention claimed is: 
     
       1. A method of curing cement to reduce autogenous shrinkage comprising:
 providing a mixture comprising cementitious material, water and carboxylated bleached wood pulp fiber; 
 allowing the mixture to cure; 
 the cementitious material comprises cement; 
 the carboxylated fibers have a carboxyl content of 10 to 70 meq/100 g of cellulose fiber; 
 the carboxylated fibers are 0.1 to 5% by weight of the dry weight of the cementitious material; 
 the carboxylated fibers are made by the oxidation process and stabilized to convert aldehyde groups to carboxyl groups; and, 
 the water to cement material ratio is a high performance concrete ratio. 
 
     
     
       2. The method of  claim 1 , wherein the fibers have a carboxyl content of 20 to 60 meq/100 g of cellulose fiber. 
     
     
       3. The method of  claim 1 , wherein the fibers have a carboxyl content of 30 to 50 meq/100 g of cellulose fiber. 
     
     
       4. The method of  claim 1 , wherein the fibers are 025 to 0.75% by weight of the dry weight of the cementitious material. 
     
     
       5. The method of  claim 1 , wherein the cementitious material further comprises aggregate material. 
     
     
       6. The method of  claim 5 , wherein the fibers have a carboxyl content of 20 to 60 meq/100 g of cellulose fiber. 
     
     
       7. The cementitious structure of  claim 5  wherein the fibers have, a carboxyl content of 30 to 50 meq/100 g of cellulose fiber. 
     
     
       8. The cementitious structure of  claim 5 , wherein the fibers have a carboxyl content of 35 to 45 meq/100 g of cellulose fiber. 
     
     
       9. The method of  claim 5 , wherein the fibers are 0.25 to 0.75 by weight of the dry weight of the cementitious material. 
     
     
       10. A method of reducing the autogenous shrinkage of cement or concrete comprising:
 providing a mixture comprising cementitious material, water and carboxylated bleached wood pulp fiber; 
 allowing the mixture to cure; 
 the carboxylated fibers have a carboxyl content of 10 to 70 meq/100 g of cellulose fiber; 
 the carboxylated fibers are 0.1 to 5% by weight of the dry weight of the cementitious material; 
 the carboxylated fibers are made by the oxidation process and stabilized to convert aldehyde groups to carboxyl groups; and 
 the water to cement material ratio is a high performance concrete ratio.